From a production standpoint, the cheaper you plan to sell something, the faster you have to produce it and at the lowest cost.
So how that translates to pipes is, to make a $20 basket pipe that the manufacturer sells for $10, with $3-$5 of material in it, he has to make the things FAST, and be willing to compromise. That $20 pipe may smoke great if everything works out, but the fit and finish will be low. If the drilling is way off or there is a huge pit in the side, the pipe is still going to market because there isn't room to cull pipes because of imperfections. Some manufacturers are better at putting more attention to details into a cheap pipe, so if you can hand pick, or if you just get lucky, some of these pipes can smoke just fine. The stem will be very basic, no hand work or refinements to it, but it may (or may not) be pretty awful.
This basic tradeoff exists all the way up the line, with more room for hand work as the price/profit goes up. The more expensive a pipe is the more the manufacturer has the option for hand work, culling bad pipes and adding steps the cheaper pipe producers just dont have the option to do. Now, the ability to add more detail and attention to a pipe doesn't guarantee they will do it, just that the ability to becomes an option.
For my money, I'd say Dr. Grabow makes a fine under $100 pipe. After that you'd want to get into the $100-$150 factory produced stuff, or hand finished by guys like Chris Askwith, Wayne Teipen or Trevor Talbert.
For a 100% hand made pipe with hand cut (comfortable, durable, well engineered) stem, you are going to spend $250 at a bare minimum probably more like $300. There aren't really exceptions to this except for very new carvers, and then there isn't a guarantee the quality is up to snuff though you will get an individuals artistic expression and that can be worth something over a factory pipe.